US4926983A - Hydraulic shock absorber - Google Patents

Hydraulic shock absorber Download PDF

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Publication number
US4926983A
US4926983A US07/300,872 US30087289A US4926983A US 4926983 A US4926983 A US 4926983A US 30087289 A US30087289 A US 30087289A US 4926983 A US4926983 A US 4926983A
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US
United States
Prior art keywords
shock absorber
slide
piston
rotary adjuster
rotary
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US07/300,872
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English (en)
Inventor
Bernd Taubitz
Peter Zieher
Claus Kramer
Kurt Engelsdorf
Armin Schuelke
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Robert Bosch GmbH filed Critical Robert Bosch GmbH
Assigned to ROBERT BOSCH GMBH reassignment ROBERT BOSCH GMBH ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: ENGELSDORF, KURT, KRAMER, CLAUS, SCHUELKE, ARMIN, TAUBITZ, BERND, ZIEHER, PETER
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Publication of US4926983A publication Critical patent/US4926983A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
    • F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
    • F16F9/32—Details
    • F16F9/44—Means on or in the damper for manual or non-automatic adjustment; such means combined with temperature correction
    • F16F9/46—Means on or in the damper for manual or non-automatic adjustment; such means combined with temperature correction allowing control from a distance, i.e. location of means for control input being remote from site of valves, e.g. on damper external wall
    • F16F9/461—Means on or in the damper for manual or non-automatic adjustment; such means combined with temperature correction allowing control from a distance, i.e. location of means for control input being remote from site of valves, e.g. on damper external wall characterised by actuation means
    • F16F9/462—Rotary actuation means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G17/00—Resilient suspensions having means for adjusting the spring or vibration-damper characteristics, for regulating the distance between a supporting surface and a sprung part of vehicle or for locking suspension during use to meet varying vehicular or surface conditions, e.g. due to speed or load
    • B60G17/06—Characteristics of dampers, e.g. mechanical dampers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
    • F16F15/00—Suppression of vibrations in systems; Means or arrangements for avoiding or reducing out-of-balance forces, e.g. due to motion
    • F16F15/02—Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems
    • F16F15/023—Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems using fluid means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
    • F16F15/00—Suppression of vibrations in systems; Means or arrangements for avoiding or reducing out-of-balance forces, e.g. due to motion
    • F16F15/02—Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems
    • F16F15/03—Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems using magnetic or electromagnetic means
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/8593—Systems
    • Y10T137/86493—Multi-way valve unit
    • Y10T137/86718—Dividing into parallel flow paths with recombining
    • Y10T137/86734—With metering feature

Definitions

  • the invention relates to a hydraulic shock absorber as defined herein.
  • a shock absorber of this type is known (German Patent No. 33 12 899).
  • This known hydraulic shock absorber has a stepping motor, with which a rotary slide is rotated in increments until the rotary slide faces corresponding openings in the piston rod.
  • the stepping motor operates by the reluctance principle.
  • a magnetically conductive sheath has soft magnetic cams that are attracted by electromagnets located in the stator and are thereby rotated into a predetermined position.
  • the drive is based on the different magnetic conductances brought about by the cams. It is therefore impossible to use a smooth-surfaced rotor.
  • the stator winding of the drive comprises a plurality of coils, through which current flows in alternation.
  • the torque is therefore always produced by only a single coil at a time, which means that a large proportion of the available winding space at a given moment goes unused.
  • a restoring spring is provided, but its use also has disadvantages.
  • the known shock absorber has a piston with mechanical compression springs for a basic damping valve, only a bypass throttle cross section is changed by the aforementioned rotary slide valve.
  • the total cross section is limited by the rod diameter and cannot be optimally adapted to a required total flow.
  • the hydraulic shock absorber of the type described above improved by the characteristics set forth herein has an advantage over the prior art that it has a continuous-adjustment system, which can effect a graduated or continuous adjustment depending on how it is triggered.
  • the entire throttle cross section of the damping piston is adjusted; thus no stepping motor is used, and if a graduated adjustment is intended, the number of stages is limited only by the resolution of the position sensor.
  • the step size is accordingly variable and can be used to linearize the characteristic force/travel curve of the damper.
  • Continuous adjustment can be optimized by using particular control cross sections. Since the adjustment system is equipped with permanent magnetic poles in the rotor, it still furnishes torque when it is currentless, and this torque is advantageously utilized to effect a safety reset, thus obviating a restoring spring.
  • Another advantage is that the rotating parts are provided with a smooth surface. This reduces the fluid friction and the damping of the adjustment system. Therefore, the viscosity of the damper fluid and its temperature dependency do not need to be taken into account in triggering the adjuster.
  • the winding of the proposed drive comprises a single coil. This makes production of the winding simpler, and the available winding space is optimally exploited to generate torque.
  • Another advantage is that only the entire throttle cross section is adjusted. Because the rotary slide is disposed in, rather than above the piston rod, the throttle cross section is easily adaptable to the required total flow by selecting the rotary slide diameter.
  • the shock absorber according to the invention has the advantage of high torque, a low moment of inertia, lesser damping of the damper adjustment, a small rotational angle, and reduced friction.
  • FIG. 1 is a sectional view of the shock absorber
  • FIG. 2 is a sectional view of a stator of the rotary adjuster
  • FIGS. 3a and 3b show the rotor of the rotary adjuster in front and side view
  • FIG. 4 is a developed view of the cylinder jacket face of the rotary slide.
  • FIG. 5 is a section through the rotary control slide and fixed control slide.
  • a hydraulic shock absorber 1 has a cylindrical jacket tube 2, provided at the bottom with a base 3 with which it is secured to a vehicle axle, not shown.
  • the upper end of the jacket tube 2 is closed with a cap 4, which has a pressure-tight duct 5 for a piston rod 6, the upper end of which is connected to a vehicle body, not shown.
  • the piston rod 6 is connected to a damper piston 7, which is slidably movable in the jacket tube 2.
  • a seal 8 in the damper piston 7 on the interior of the shock absorber divides two work chambers 9 and 10 from one another.
  • the piston rod 6 and the damper piston 7 are hollow; the damper piston 7 has a housing 11 with a recess 12 for receiving an electromagnetic rotary adjuster 13 and a hydraulic control slide 14.
  • a position sensor 16 is provided in an extension 15 of the piston housing 11.
  • a gas-filled compensation chamber 17 also adjoins the work chamber 9, being divided from the chamber 9 by a piston 18 and serving to equalize the volume when the piston rod 6 is extended and retracted.
  • a housing flange 19 is screwed into the piston housing 11 from the top and has a plurality of axial openings 20, distributed uniformly around its axis for the fluid to flow through.
  • An upper tubular extension 21 of the flange 19 receives the inner end of the piston rod 6 and is provided with a sealing plug 22 which seals an electrical lead duct for electrical conductors 23 which are connected with an electronic control unit.
  • a lower tubular extension 24 of the flange 19 includes a ball bearing 25 for a rotary adjuster shaft 26, into which a crosspin 27 is diametrically pressed, directly below the ball bearing 25. The ends of the crosspin protruding from the shaft 26 are received by a groove 28 of the tubular extension 24.
  • the groove 28 extends azimuthally over an angle that is larger than the adjusting range of the rotary adjuster 13 (see also FIG. 5).
  • the rotary adjuster 13 inserted into the piston housing recess 12 comprises a stator 30 and a permanent magnetic rotor 31.
  • the stator has a stator lamination packet 32 and a winding 33 with a winding lead 34.
  • the individual stator parts are shown again in FIG. 2, which is a cross section through the stator lamination packet 32.
  • the packet has two oppositely disposed teeth 35 and 36, two grooves 37 and 38 and a magnetic short circuit 39.
  • a coil 40 which is divided into two halves 41 and 42, is inserted into the grooves 37 and 38.
  • the two coil halves 41 and 42 are connected in series and each is wound about a respective tooth 35 and 36.
  • the coil winding 33 is laid into the grooves through the openings 43 and 44 in the grooves 37 and 38.
  • FIGS. 3a and 3b show the rotor 31 of the rotary adjuster 13. It is embodied as a hollow cylinder 45, which is made of a hard magnetic material such as Seemorium-Cobalt SmCo and is magnetized diametrically, as the arrows 46 indicate. Its inner and outer jacket faces 47 and 47' are polished smooth. Its outer circumference is approximately equal to the outer circumference of the piston rod 6.
  • the control slide 14, which is actuatable by the rotary adjuster 13 has a rotary slide 48, which is embodied by enlarging the lower part of the shaft 26.
  • the rotary slide 48 has radial openings 52 as control openings and is inserted into a housing recess of the damper piston 7, which as a fixed hollow-cylindrical slide 53 is likewise provided with radial openings 54 as control openings.
  • the rotary slide 48 and slide 53 are shown again in section in FIG.
  • the seven possible adjusting steps are each embodied such that in each adjusting range, the slide 48 is rotated such that a predetermined number of slits 52 is rotated to a position in front of the openings 54.
  • the hydraulic throttle cross section at any given time is the sum of all the slits 52 of the six control ranges that arrive in a position in front of all of the openings 54 and a gap between the rotary slide 48 and fixed slide 53 formed upon assembly.
  • FIG. 4 a developed view of the rotary slide 48 is shown. It can be seen that the rotary slide has seven stages, which are embodied by the openings 52 of the rotary slide 48. Of these, the first stage is a closed stage, which by leakage determines the basic flow through the shock absorber. Of the other six stages, only four are shown in FIG. 4.
  • the permanently excited rotary adjuster 13 adjusts the hydraulic throttle cross section in the control slide 14 in accordance with vehicle and road conditions; the damper fluid flow from one work chamber to the other in the shock absorber flows only through this throttle cross section.
  • the winding 33 of the electromagnetic rotary adjuster 13 is supplied by an alternating current bridge circuit (H circuit); that is, two current directions are made available and when given a bipolar supply, the permanent-magnetic rotor 31 of the electromagnetic rotary adjuster has two torque directions.
  • the torque of the rotary adjuster is the result of the cooperation of the coil field and of the permanently excited rotor field.
  • the direction of the adjusting moment is determined by the current direction at the time.
  • the absolute maximum torque is attained in the position in which the stator field and rotor field form an angle of 90° with one another, if the armature recoil is ignored.
  • the center of the permanent magnetic rotor poles at the air gap is opposite the groove openings 43 and 44 (FIG. 2).
  • the course of the torque is approximately trapezoidal over an angular range of +90° for a fixed current intensity.
  • the maximum adjusting range is located symmetrically with respect to the above-mentioned position and is limited to 30°.
  • the electromagnetic rotary adjuster 13 has a further torque as well, which results from the force of attraction between the magnet poles and the stator teeth 35 and 36.
  • This locking moment which is superimposed on the adjusting moment, also occurs when the coil is currentless. It turns the rotor 31 toward either the first or the second stator tooth, depending on the rotor position at the time. The motion in the currentless state is limited by the stop 27/28.
  • the jacket face is divided into control zones 55 and closing zones 56. While the closing zones 56 comprise solid material, the control zones 55, in this version, are represented by control slides 57 of various lengths and widths.
  • the hydraulic cross section is varied, which takes place in seven stages.
  • the actual control edge, embodied by one side of the opening 54, is positioned at a web in the middle between two control slides 57.
  • the basic damping with complete coincidence of the opening 54 and the closing zone 56, is assured by the basic flow.
  • the characteristic damper curve of the damper force over the angle can be adapted by suitably dimensioning the control faces.
  • Other possible versions provide the option of continuous adjustment of the throttle cross section, for instance having rectangular, triangular or other shapes of openings in the control zones, with which the characteristic curve of damper force over angle can easily be adapted.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Electromagnetism (AREA)
  • Vehicle Body Suspensions (AREA)
  • Fluid-Damping Devices (AREA)
US07/300,872 1988-02-25 1989-01-24 Hydraulic shock absorber Expired - Lifetime US4926983A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3805934A DE3805934A1 (de) 1988-02-25 1988-02-25 Hydraulischer stossdaempfer
DE3805934 1988-02-25

Publications (1)

Publication Number Publication Date
US4926983A true US4926983A (en) 1990-05-22

Family

ID=6348165

Family Applications (1)

Application Number Title Priority Date Filing Date
US07/300,872 Expired - Lifetime US4926983A (en) 1988-02-25 1989-01-24 Hydraulic shock absorber

Country Status (5)

Country Link
US (1) US4926983A (ko)
EP (1) EP0329950B1 (ko)
JP (1) JPH01249508A (ko)
KR (1) KR890013378A (ko)
DE (2) DE3805934A1 (ko)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5025899A (en) * 1986-06-05 1991-06-25 Lizell Magnus B Method and apparatus for absorbing mechanical shock
US5034670A (en) * 1989-04-21 1991-07-23 Mitsubishi Denki K.K. Control circuit for electromagnetic actuator
US5217095A (en) * 1986-06-05 1993-06-08 Monroe Auto Equipment Company Method and apparatus for absorbing mechanical shock
US5303803A (en) * 1990-04-07 1994-04-19 August Bilstein Gmbh & Co. Kg Variable dashpot for motor vehicles
US5305860A (en) * 1989-03-03 1994-04-26 Maremont Corporation Remote controlled vehicle damper
US5307907A (en) * 1991-06-11 1994-05-03 Atsugi Unisia Corporation Hydraulic damper
US5350187A (en) * 1992-10-16 1994-09-27 Monroe Auto Equipment Company Adjustable damping system
US5624165A (en) * 1994-10-26 1997-04-29 Daewoo Electronics Co., Ltd. Apparatus for controlling brake pressure applied to the wheels of automobiles using pressure fluid
US6286642B1 (en) * 1999-10-18 2001-09-11 Giant Mfg. Co., Ltd Fluid regulating device for use with a shock-absorbing cylinder to obtain a variable shock absorbing effect
US20100187059A1 (en) * 2009-01-23 2010-07-29 Jri Development Group, Llc Linear impelled module damper
US20110079476A1 (en) * 2009-10-07 2011-04-07 Laurence James Holt Hydraulic damper spool valve

Families Citing this family (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3928993A1 (de) * 1989-06-29 1991-01-03 Bosch Gmbh Robert Fahrwerksregelung mit stellglied-anpassschaltung
DE3940290C1 (en) * 1989-12-06 1991-07-11 August Bilstein Gmbh & Co Kg, 5828 Ennepetal, De By=pass valve drive for hydraulic vibration damper - has electro-rotor fixed to control disc via toothed rod
DE4002883A1 (de) * 1990-02-01 1991-08-08 Bilstein August Gmbh Co Kg Schwingungsdaempfersteuerventil eines bypasses mit selbsthaltung
DE4039236C1 (en) * 1990-02-01 1992-05-27 August Bilstein Gmbh & Co. Kg, 5828 Ennepetal, De Control valve for hydraulic shock absorber of motor vehicle - uses electromagnet to increase force of permanent magnet and open by=pass against mechanical spring force closing by=pass
US5207774A (en) * 1991-11-27 1993-05-04 Lord Corporation Valving for a controllable shock absorber
DE4142862C2 (de) * 1991-12-23 1994-06-16 Bilstein August Gmbh Co Kg Regelbarer Schwingungsdämpfer für Kraftfahrzeuge
JP3383863B2 (ja) * 1993-03-08 2003-03-10 トキコ株式会社 減衰力調整式油圧緩衝器
DE102011102835B4 (de) 2011-05-30 2015-07-02 Audi Ag Hydraulischer Stoßdämpfer mit Proportionalmagneten
DE102014215566B3 (de) * 2014-08-06 2016-01-21 Zf Friedrichshafen Ag Dämpfventil
US20160153515A1 (en) * 2014-12-02 2016-06-02 Cycling Sports Group, Inc. Valve Assembly For Bicycle Suspension System
DE102015201957A1 (de) * 2015-02-04 2016-08-04 Volkswagen Aktiengesellschaft Hydraulischer Schwingungsdämpfer
CN104776152B (zh) * 2015-04-08 2017-01-25 重庆大学 高效能低功耗磁流变半主动与主动一体化减振装置
CN112303167B (zh) * 2020-11-19 2022-05-17 扬中市兴鸿车辆配件有限公司 一种阻尼独立悬挂的液压减震器及其液压阻尼系统

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4527676A (en) * 1982-02-13 1985-07-09 Atsugi Motor Parts Co., Ltd. Variable-damping-force shock absorber
US4645042A (en) * 1983-12-21 1987-02-24 Jidosha Denki Kogyo Kabushiki Kaisha Hydraulic damper
US4660686A (en) * 1983-09-24 1987-04-28 August Bilstein Gmbh & Co Kg Adjustable shock absorber, especially for motor vehicles
US4671392A (en) * 1984-12-18 1987-06-09 Fichtel & Sachs Ag Vibration damper with variable damping force
US4681143A (en) * 1984-12-27 1987-07-21 Toyota Jidosha Kabushiki Kaisha Electromagnetic directional control valve
DE3635894A1 (de) * 1986-10-22 1988-05-05 Bosch Gmbh Robert Stossdaempfer
US4754855A (en) * 1985-09-19 1988-07-05 Aishin Seiki Kabushiki Kaisha Apparatus for driving rotary valve of shock absorber

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB664770A (en) * 1949-03-30 1952-01-09 Woodhead Monroe Ltd Improvements in hydraulic shock absorbers
DE1084528B (de) * 1958-06-10 1960-06-30 Hoesch Ag Regelbarer hydraulischer Stossdaempfer
JPS5872546U (ja) * 1981-11-12 1983-05-17 トキコ株式会社 減衰力調整式油圧緩衝器
US4526401A (en) * 1982-11-30 1985-07-02 Atsugi Motor Parts Co., Ltd. Electronic control system for adjustable shock absorbers
DE3312899C2 (de) * 1983-04-11 1985-06-13 F & O Electronic Systems GmbH & Co, 6901 Neckarsteinach Regelbares Ventil für die Kolbenstange eines Schwingungsdämpfers
DE8336759U1 (de) * 1983-04-11 1985-11-28 F & O Electronic Systems GmbH & Co, 6901 Neckarsteinach Stoßdämpfer mit veränderbarer Dämpfungscharakteristik
JPS6026345U (ja) * 1983-07-29 1985-02-22 トキコ株式会社 ハイドロ・ニュ−マチック　サスペンション

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4527676A (en) * 1982-02-13 1985-07-09 Atsugi Motor Parts Co., Ltd. Variable-damping-force shock absorber
US4660686A (en) * 1983-09-24 1987-04-28 August Bilstein Gmbh & Co Kg Adjustable shock absorber, especially for motor vehicles
US4645042A (en) * 1983-12-21 1987-02-24 Jidosha Denki Kogyo Kabushiki Kaisha Hydraulic damper
US4671392A (en) * 1984-12-18 1987-06-09 Fichtel & Sachs Ag Vibration damper with variable damping force
US4681143A (en) * 1984-12-27 1987-07-21 Toyota Jidosha Kabushiki Kaisha Electromagnetic directional control valve
US4754855A (en) * 1985-09-19 1988-07-05 Aishin Seiki Kabushiki Kaisha Apparatus for driving rotary valve of shock absorber
DE3635894A1 (de) * 1986-10-22 1988-05-05 Bosch Gmbh Robert Stossdaempfer

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5025899A (en) * 1986-06-05 1991-06-25 Lizell Magnus B Method and apparatus for absorbing mechanical shock
US5217095A (en) * 1986-06-05 1993-06-08 Monroe Auto Equipment Company Method and apparatus for absorbing mechanical shock
US5305860A (en) * 1989-03-03 1994-04-26 Maremont Corporation Remote controlled vehicle damper
US5034670A (en) * 1989-04-21 1991-07-23 Mitsubishi Denki K.K. Control circuit for electromagnetic actuator
US5303803A (en) * 1990-04-07 1994-04-19 August Bilstein Gmbh & Co. Kg Variable dashpot for motor vehicles
US5307907A (en) * 1991-06-11 1994-05-03 Atsugi Unisia Corporation Hydraulic damper
US5350187A (en) * 1992-10-16 1994-09-27 Monroe Auto Equipment Company Adjustable damping system
US5624165A (en) * 1994-10-26 1997-04-29 Daewoo Electronics Co., Ltd. Apparatus for controlling brake pressure applied to the wheels of automobiles using pressure fluid
US6286642B1 (en) * 1999-10-18 2001-09-11 Giant Mfg. Co., Ltd Fluid regulating device for use with a shock-absorbing cylinder to obtain a variable shock absorbing effect
US20100187059A1 (en) * 2009-01-23 2010-07-29 Jri Development Group, Llc Linear impelled module damper
US8733519B2 (en) 2009-01-23 2014-05-27 Jri Development Group, Llc Linear impelled module damper
US20110079476A1 (en) * 2009-10-07 2011-04-07 Laurence James Holt Hydraulic damper spool valve
US8235186B2 (en) 2009-10-07 2012-08-07 Multimatic Inc. Hydraulic damper spool valve

Also Published As

Publication number Publication date
EP0329950A2 (de) 1989-08-30
DE3805934A1 (de) 1989-09-07
DE58905930D1 (de) 1993-11-25
EP0329950B1 (de) 1993-10-20
EP0329950A3 (en) 1990-03-28
KR890013378A (ko) 1989-09-22
JPH01249508A (ja) 1989-10-04

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